That's why when I use Mode 2 to get my focus dialed in, I always switch back to full color rendering to check first before making the exposure. I find it often needs that tiny mm or so tweak.

I do it exactly the other way around.... and I can honestly say that I've never missed the point of focus when shooting a stationary object.

On the Ricoh's APS-C format, the same lens has nearly a stop and a half more DoF than on 35mm film, and focusing via the viewfinder is even harder.

DOF is about 1.5x bigger on the GXR; so it would be about f/6.8 when shot wide open. Still, focusing this lens is not very hard, when combining MODE2 and 8x enlargement. Never had any problems as of yet.